Internal combustion engines are known to generally comprise a lubrication system with which a disposable filter cartridge is associated contained in a cup, which it is not necessary to describe in detail.
Said cartridge is intended to be removably coupled, generally by a threaded system and by way of suitable interposed seal means, to a base provided on the engine structure and comprising a suitable seat.
The base of said cartridge is provided with apertures for the entry of the oil to be filtered and for the exit of the filtered oil, said seat presenting corresponding arrival and departure channels for the oil to be filtered and for the filtered oil respectively.
Engines exist in which the cartridge carrying seat generally faces downwards, and others in which it generally faces upwards.
Sunken regions which fill with oil during engine operation are generally present at the mutually facing surfaces of said seat and said cartridge.
When the cartridge is to be removed, for example for its replacement, at least a part of the oil present in said regions is no longer retained, hence is free to pour out of the base.
If the cartridge carrying seat generally faces downwards, the loss of said oil fraction is generally not a problem because the oil is retained by the cup of the cartridge.
However if the cartridge carrying seat faces generally upwards, the loss of said oil fraction can be a problem for at least one of the following reasons: soiling of engine parts and accessories reaching high temperature, oil seepage into electrical and/or electronic equipment, dirtying of the engine compartment and panels, and contamination of the workplace floor.